Don't emit the LC_CTYPE-not-set warning more than once.
* pinentry/pinentry.c (lc_ctype_unknown_warning): New variable. (pinentry_utf8_to_local): Only emit the LC_CTYPE warning if lc_ctype_unknown_warning is not set. After emitted such a warning, set lc_ctype_unknown_warning. (pinentry_local_to_utf8): Likewise.